Also, not everyone wants to be a manager, he says. “It means more direct interaction with people who may not want to take direction from you, more responsibility, and in many cases, longer hours and more stress. Not everyone wants to be in charge or to be in the spotlight.”

Another reason: more and more employees want a work-life balance where work isn't necessarily their highest priority, Teach adds. “There are many people whose top priority is raising a family and work comes second.” When that's the case, becoming a manager can make you less available at home.

Finally, he says, “there are many people who are really good at what they do; they enjoy their work, and they don't want to jeopardize that with a promotion to management.”

If you yourself have no plans or aspirations for taking on a managerial position, you should make your intent clear from the beginning, says Debra Benton, an executive coach and author of The Virtual Executive: How to Act Like a CEO Online and Offline.“Let your employer know that you’ll work hard even though you have no desire to get into management,” she says. “Tell your employer that if they like your work and want to reward you, they should do it in the form of compensation or benefits. And remind them that not wanting a promotion is not a sign of lack of ambition.”

In fact, you can be extremely successful in a non-managerial position.

For some, reaching the top rung of the corporate ladder means joining the C-Suite and dealing with the long hours, politics, stress, and other challenges that come with the big title and financial rewards, Teach says. For others, success means finding a job that they like and are content with, one that allows them to provide for their families without them becoming overwhelmed by difficult deadlines and difficult people. “If you're really good at your job, and others around you acknowledge that, then you are successful. If your work contributes to the team's success, then you are successful. Success isn't always determined by your title or salary.”

But even if you do your job well and have a successful career—once you hit a certain age and pay grade, you’re likely to be a target when the bean counters come sniffing around.

“If you're content with staying in your present position and your department has recently hired a newbie just out of college who is aggressive, ambitious, and enthusiastic, you may need to watch your back, especially if they can do your job for less money,” Teach says. This doesn't necessarily mean that your job is in jeopardy, but if you feel that it may be threatened, have an honest conversation with your supervisor and see what he or she is thinking, he suggests.

So how do you defend your job against the young professionals fresh out of college who can do what you do for much less? And how do you prove to your employers that you’re worth keeping?

There are several things you can do, Teach says.

Be great at what you do.

Every supervisor wants results and if you give them results and make their job easier, it will be difficult for them to get rid of you, he says.

“Do your job 110%,” Benton adds. “The 100% is in the specialty required. The 10% is in your positive attitude at work, your treatment with respect towards others, your willingness to help others, your interest in learning other jobs so you better understand your piece of the puzzle and how it fits in, and your example to others of honesty, hard work, and good intent.”